A biography of coronaviruses from IBV to SARS-CoV-2, with their evolutionary paradigms and pharmacological challenges

Abstract

Coronaviruses (CoVs) are a family (Coronaviridae) of viruses that cause respiratory disorders in birds and mammals. They were originally discovered as infectious bronchitis virus (IBV) of chickens in the early 20th century. A group of related viruses subsequently discovered from mice and humans led to the collective naming as coronaviruses, as they were all characterized by a solar corona-like ring on their surface, called the spikes. The first known human CoVs were among viruses that cause common cold and considered as modest threats to human health. But the emergence of zoonotic CoVs such as severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and Severe acute respiratory syndrome-related coronavirus  (SARS-CoV-2) during every recent past decade resulted in pandemics with loss of human lives. With no vaccine to prevent, and no drug to treat the infections, the miniscule viruses evolve into behemoths of plagues. SARS-CoV-2 with its infection, COVID-19, is particularly rampant and malicious and is bound to cause colossal impacts not only on human health but also on global economy. Understanding of their evolutionary strategies and pathogenic adaptions had given us fair warnings. Yet, the world was ill-prepared. This article highlights the scientific messages that could have mitigated the COVID-19 pandemic, the evolutionary mechanisms in SARS-CoV-2 and related CoVs that bely drug and vaccine development, and above all, the possible epidemics in the future.